yielding spacer



1956 D. H. PIERCE YIELDING' SPACER 'Filed Feb. 16, 1952 m M 082 W yUnited States Patent This invention 'relates t'o a y'ielding spacerbetween two .or' "more relatively movable impact members and more "Iparticularly to a spacer for motio'n'transmitting devices,-"fo're'xarnple, in a valve operating means for engines,

commonly referred to as valv'et'appets, o'r dampen- :Ijn'gand.slacltadjusting device'sis'uch as "shock absorbers,

:door checks, or the like.

"""trated-- and" described in .my United States 'The invention primarilyrelates to improvements illus- Patents 2,570,853'and 2,570,854, issuedOctober 9', l951,"wherein a'yieldingclutching means is disclosed for usein the valve"'operating" mechanism of an internalcombustion ""en'gine'tocompens'atefor the variations inlength of the valve stem' caused bytemperature changes and Wear.

"'Iti the aboveidentified-patents there is disclosed a pair ofintercommunicating chambers, each of variable capacity, having ameans'forper'mittingl restricted flow ofmaterial' from'one chambertothe"other.. The material in'the chambers is described as a mass ofsoft, solid but flowable, viscous material which is highly resistant "to"suddendeformation butfreely' fiowable under sustained pressure. Itis'an object of the present invention to provide improved means forregulating the flow of material from W one chamber to the other.

It is a furtherobject oftheinvention topr'ovide a restrictionbetweenth'e twdcha'mbers which will permit a predetermined'rate of "flowof the material in one directionand adifierentuate of flow in anopposite direction.

Other objects and"advantage's of the invention will "more fully appearfrom the following. description "taken in connection with theaccompanying drawings, in which:

,Fig. 1 is'a sectional view of a valve operating mecha- -'nism"mbodyingmyimproved' connection between a valve stem and a tappet of aninternal'combustion, engine,

parts being shown broken'away in section and 'parts in elevation;

Fig. 2 is' an' enlarged, fragmentary view of the restric- *tion meansbetweenthe interconnected chambers, shown Fig.-3is across sectional viewtaken on line 3-3 of Fig. 1; and

Fig. 4 is a cross sectional view taken on'lin'e 4-4 of *"Referriingtothe drawings, '1 have illustrated theinven- *"tion as applied to avalv'e tappet of an internal combustion euginel "The cylinder block ofthe engine is provided withthe usual "combustion port 12"having a valveseat l4-engageable with the usual poppetv'alve 16. The

-valve stem 18 is' slidably mounted in the block 10 and is urgedto'valve closing position' by the compression spring'20 surroundingthe'valve stem 18 and bearing between the *block 10- an'dawasher 22 held onthe'stem 18 byakey 24.

Atappetmember 26,-ernbodying my improved consanction,i's'slidablymoufited inthe "cylinder block 10,

below 'and inaaxiat alignment with *the valve s'tem '18.

2,734,495 @Patented Feb. 14,1956

2 The valve. 16 and tappet 26are periodically lifted by a cam 28-on acamshaft 30.

In the-operation of the valve mechanism the parts are --elongated byheatand the,valve. 16 moves away from the caml28, consequentlynotproperly seating on the valve seat -14, unless sufiicient. .clearanceis provided between the bottom of the .valve stem ls-and the top of the.valvetappet26. 5 .S uflicientclearance, to eliminate over expansion byheating, results in noisy operation of the parts and wear, reducing theoverall length of the parts, causes noise as .well as inefficientoperation.

The present invention is directed to a self-contained .tappet whichcompensates forwear-and expansion of the parts, maintaining zeroclearance between the valve stem and the tappet at all times.

Thetappet 26 is formed as a cylinder having a tubular fside wall 32 anda closed bottom portion 34, the latter adapted to seat on the cam 28. Anupper plunger-36 is slida-bly mounted in the open end of the tubularportion-32. The plunger. carries a tappet valve stem 38. The inner endof thetappet valvestem 38 is provided with a:tappet valve head.42. 44 isslidably mounted on the tappet valve stem 38 and A lower plunger isarranged betweenthe tappet valve head 42 and the upper plunger 36. Ashoulder 46 is provided on the .jtappet valve stem 38 and a pressuredeformable flange '48 is provided on the lower plunger 44 co-operatingwith .the shoulder 46 to provide a stop for limitingsthe slidingmovement of the lower plunger 44 on the tappet valve stem 38 toward thetappet valve head 42. A compression spring. 50 is arranged between theupper and -lower plungers 36 and-44. A lock ring 52 is provided in theinner wall of the tubular side wall 32 for limitting the outer movementof the upper plunger 36. A

- sealingring 54, of flexible material such as rubber, is

carried in a groove 58 in the wall of the plunger 36 for sealingengagement with the inner periphery of the tubular side wall 32, at itsouter open end.

The lower: plunger. 44 forms a chamber; with thetubular sidewall 32 andits closed end 34. This chamber. is divided .into an upper chamber A anda lower chamber B by the tappet valve head 42. n

. A-predetermined quantity of flowablematerial is placed in the chambersAand B at the opposite sides of the tappet valve head 42. As one exampleof the flowable material which may be successfully used,-reference. is

..again made to my patents, above referred to, wherein I have used asilicone elastic polymer compound which has'a marked cold flowcharacteristic.

The material is a doughy, putty like compound, largely F inorganiccomposition,- free from vulcanizing agents and is cured, thereby'uotbreaking downtrom use or age. Its properties are not materially affectedby temperatur'es far above and below the serviceable limits of naturalor synthetic organic rubbers. Thismaterial shows slight property changesin temperatures ranging from approximately minus 75 F. to plus 450 FL Itis therefore suitable. for working temperatures in an internal 60"flo'wable material, during operation, that is, there'should combustion.

It is highly desirable to vary the'rate of flow of the be an. increasedflow of material from chamber A to chamber B during the'period in whichthe valve 16 is closed over the period in which the valve 16 is open.

Referring more specifically to Fig. 2, I have shown a means foraccomplishing the above result The tappet valve head 42 has an outerdiameter less than the diameter of the inner periphery of the cylinder32 so that the material may'flow around the valve head 42 from chamber Ato chamber B, or vice versa. To increase tlie flow of material fromchamber A to chamber B, I have provided a chokering 60 co-operating'withthevalve A head 42. The valve head 42 has its inner face providedpression spring 66, exerting a force less than the spring 59, lsarranged in the chamber B between the choke ring 69 and the bottom wall34 of the tappet 26 for urging the tapered face 64 of the choke ring 60normally into contact with the tapered seat 62 of the valve head 42.

The outer diameter of the choke ring 60 is greater than the outerdiameter of the valve head 42 but is less than the diameter of the innerwall of the cylinder 32 so that there may be a flow of the materialaround the outside of the choke ringbt) but less than the flow ofmaterial around the valve head 42 when the choke ring surface 64 ismoved away from the valve head seat 62. Thus, the material may flow fromthe chamber A to chamber B in greater volume than in flowing fromchamber B to chamber A.

When the parts are assembled, the dough-like material is placed in thechambers A and B on opposite sides of the tappet valve head 42. Thelower plunger 44, with the lock ring 45 in place, is then slid in thecylinder with the upper plunger 36. A sealing ring 56 is providedbetween the lower plunger 44 and the flowable material to preventleakage around the valve stem 38 and the side wall of the cylinder 32.If desired, the flowable material may be placed in the chamber B, thenthe spring 66, choke ring 60, and valve head 42 with its assembled stem33, lower plunger 44, spring 56 and upper plunger 36. the spring 66,choke ring 66, and valve head 42 to sink into the flowable material, sothat the latter is on opposite sides of the valve head 42 and the partsare immersed in the material.

This assembly is done in a vacuum so that all air is removed from thechambers A and B and the flowable material.

Tie pring 59, after the tappet parts are assembled into a self-containedunit, urges the upper plunger 36 outwardly into engagement with thelocking ring 52 and the lower plunger 44 into pressure engagement withthe flowable material in chambers A and B.

When the tappet assembly is in operating position between the valve stem18 and the cam 28, the upper plunger 36 is moved inwardly of the tappetcylinder 32 by the pressure of the spring 20. The load force of thespring 50 on the plunger 36 is less than the load of the spring 20 onthe valve stem 18 so that the plunger 36 is moved inwardly of the tappetcylinder, thereby adjusting the overall dimension of the tappet to adistance corresponding to the distance between the lower end of thevalve stem 18 and the outer surface of the cam 28.

The inward movement of the plunger 36 causes inward movement of thetappet valve head 42. The outer diameter of the valve head 42 is lessthan the inner diameter of the chamber A and B. As the valve head 42 ismoved inwardly, the flowable material in chamber B is moved through thepassage between the outside diameter of the choke ring 60 and thecylinder 32 into the chamber A.

Sudden shock or a blow on the material, as caused by lifting the valve16, will be transmitted through the material without appreciable flow,but there will be a slight extrusion of the material through the spacebetween the cylinder wall 32 and the outer periphery of the choke ring60, transferring the material from chamber B to pensating action causesrelative axial movement of the Pressure on the valve stem 33 will causecylinder 32 and the upper plunger 36, increasing or decreasing theoverall length'of the tappet assembly.-

If there is clearance between the end of the valve stem 13 and the valvetappet 26, the spring 50 will urge the plunger 36 and valve head 42axially of the cylinder 32 and force the material in chamber A aroundthe valve head 42 and choke ring 60 into chamber B, thereby raising theplunger 36 to contact the end of the valve stem 18, and compensate forthe clearance. Continued outward movement of the plunger 36 is resistedby the pressure of the spring 20 which is greater than the pressure ofthe spring 50. The material may flow from the chamber A to the chamber Bin greater volume than in flowing from chamber B to chamber A. Theplunger 36 is moved outwardly of the cylinder 32 more rapidly than it ismoved inwardly of the cylinder.

The operation of the device is as follows: When the valve 16 opens animpact load is transmitted from the upper plunger 36 to the flowablematerial in chamber B. This impact is resisted by the rheologicalcharactertistics of the llowable material and the restriction caused bythe choke ring 60 in the annular orifice around the tappet valve head4-2. Some leak-down will occur by passage of the material around theoutside of the choke ring 60, the latter now in pressure contact withthe tappet valve head 42 and the pressure of the spring 66 during thetime that the engine valve 16 is open. When the valve 16 closes,adjustment in length must be made to compensate for this leak-down andto accomplish the same at a faster rate of flow. With no load on theupper plunger 36, the spring 26 resisted by the closed valve 16, thetappet spring 56 drives the upper plunger 36 and valve head 42 upwardlyand the lower plunger 44 downwardly, forcing the llowable material fromchamber A to chamber B through the large orifice between the valve head42 and the inner surface 64 of the choke ring 60, opened by the fluidpressure moving the choke ring 60 away from the valve head seat 62against the pressure of the spring 66, as shown by the dotted lines inFig. 2.

After compensating for the leak-down, contact is made between the upperplunger 36 and the valve stem 18. The choke ring spring 66 now closesthe orifice between the choke ring 60 and the valve head 42 by movingthe choke ring 60 into contact with the valve head 42 and the tappet isready for another cycle.

The size of the orifice between the outer periphery of the valve head 42and the wall 32 may be varied to increase or decrease the amount ofmaterial passing from one chamber to the other during a predeterminedtime interval, and the size of the orifice between the outer peripheryof the choke ring 60 and the wall 32 may be varied to increase ordecrease the rate of flow of the material from one chamber to the other.

While I have illustrated and described what I deem to be a preferredembodiment of the invention, it will be understood that various changes,including the size, shape and arrangement of parts, may be made withoutdeparting from the spirit of my invention and it is not my intention tolimit its scope other than by the terms of the appended claims.

I claim:

1. In a valve tappet for use in an internal combustion engine, thecombination of a body having a bore therein which is closed at one endand open at its opposite end, a valve within said bore having oppositelydisposed side walls and having a diameter less than the diameter of thebore to permit a restricted How of viscous material between said valveand the wall of the bore, a movable end wall sealing the open end of thebore, resilient means urging said end wall inwardly, a valve rodconnected to said valve and extending through said movable and wall, achoke ring co-operating with said valve on the side of said valveadjacent the closed end of the bore, said choke ring having an outerdiameter greater than the diameter ot sai d valve and only slightly lessthan the diameter of a. se

the bore, resilient means for urging said choke ring into sealingrelation with said valve, and a mass of soft, solid but flowable viscousmaterial in the bore on opposite sides of said valve.

2. In a valve tappet for use in an internal combustion engine, thecombination of a body having a bore therein which is closed at one endand open at its opposite end, an inner movable plunger within the boreforming a chamber with the walls and closed end of the bore, an outermovable plunger within the outer open end of the bore, a compressionspring between said plungers for urging said inner plunger inwardly andsaid outer plunger outwardly, a valve stem movable inwardly by saidouter plunger and extending through said inner plunger, 21 valve carriedby said valve stem and within the chamber between said inner plunger andthe closed end of the bore, the diameterof said valve being less thanthe diameter of the bore to permit a restricted flow of viscous materialbetween said valve and the wall of the bore, a choke ring having anouter diameter greater than the outer diameter of said valve butslightly less than the diameter of the bore and co-operating with saidvalve, a compression spring between said choke ring and the closed endof the bore for urging said choke ring into seating engagement with saidvalve, and a mass of soft, solid but fiowable viscous material in thebore on opposite sides of said valve.

3. An automatic self-adjusting self-contained valve tappet comprising, ahousing, a body of fluid in the housing, yieldable loading meansconfining the fluid in a closed area of the housing, a choke ringimmersed in the body of fluid and adapted to receive fluid therearoundand therethrough, a thrust load transmitting valve coacting with saidring and controlling flow of fluid therethrough, and a relatively weakspring urging the choke ring toward the valve whereby thrust imparted tothe housing will be transmitted to the choke ring through the body offluid for transfer to the valve while permitting leakdown of fluidaround the choke ring While release of said thrust will permit the valveand ring to separate for rapid flow of fluid through the ring under theinfluence of the loading means to quickly establish the desired levelfor the ring in the fluid without transfer of fluid out of the confinedarea of the housing.

4. A clearance regulator which comprises, a body having a closed bottomand an open top, a choke ring having a free sliding fit in said body, athrust load transmitting member in said body coacting with said chokering to provide a valve, a seal slidable on said member in said body andadapted to confine hydraulic fluid in the bottom portion of the body, alower plunger slidable on said member in said body and acting on saidseal, an upper plunger in said body on said member, a return springbetween said upper and lower plungers and acting thereon tosimultaneously bottom the seal on hydraulic fluid in Lhe body and extendthe member to take up slack in the regulator, and a light spring actingon said choke ring for urging said ring against said member to close thevalve.

5. A hydraulic clearance regulator which comprises, a body having aclosed bottom and an open top, a light spring in said body on saidbottom, a ring member freely slidable in said body and bottomed on saidlight spring, a stemmed valve member having a head coacting with saidring member to provide a valve, the stem of said valve projectingcentrally through said body, a seal slidably engaging said stem andsealingly engaging said body, a lower plunger slidably engaging saidstem and backing up said seal, and stem having a reduced diameterportion and a shoulder adjacent said portion, said lower plunger havinga reduced end portion receiving the reduced diameter portion of the stemtherethrough and forming an abutment for said shoulder, an upper plungeron said stem above said reduced diameter portion of the stem, a returnspring held under compression between said plungers in said body, a sealcarried by said upper plunger coacting with said body, said body havingan internal groove adjacent the open top thereof, and a lock ring insaid groove providing an abutment for said upper plunger to retain theparts in the body.

6. A thrust valve type hydraulic tappet which comprises a tappet barrelhaving a closed bottom and on open top with a cylindrical bore betweenthe open top and closed bottom, a light spring bottomed on the bottom ofsaid barrel, a choke ring slidable in said bore and resting on saidlight spring, said choke ring coacting with said bore to provide aleakdown clearance therebetween, a stemmed thrust load transmittingvalve having coaction with said choke ring to provide a valve passagethrough the ring, a movable end wall in said tappet barrel slidable onthe stem of the valve, resilient means urging said end wall toward thebottom of the barrel to confine a body of hydraulic fluid in the barrelon opposite sides of the choke ring, a head on the stem of said valveand slidably mounted in said bore, and said head providing an abutmentcoacting with said movable end wall to retain the resilient means underload.

7. In a hydraulic tappet of the thrust load transmitting valve type theimprovement of a valve assembly adapted to confine the hydraulic fluidand to control flow of the confined fluid which comprises a valve memberhaving a stem and an enlarged head at one end thereof, valve seat meanscoacting with said head, a seal slidably mounted on said stem, an endwall slidably mounted on said stem for backing up said seal, said stemhaving an abutment coacting with said end wall to limit movement of theend wall toward the valve head, a head member on said stem in spacedrelation from said end wall, and a return spring compressibly loadedbetween said end wall and head.

8. In a hydraulic tappet including a tappet barrel, a choke ring mountedin said barrel and a light spring urging said choke ring away from thebottom of the barrel, the improvement of the valve assembly insertableas a unit in said barrel, said assembly having a stemmed valve with ahead portion coacting with said choke ring, a cup seal slidably mountedon said stem, a lower plunger slidably mounted on said stem and backingup said cup seal, said stem having a reduced diameter portion providingan abutment shoulder, said lower plunger having an inturned end portionsurrounding said reduced diameter portion of the stem and abutted bysaid shoulder, an upper plunger on the end of the stem and adapted to beslidably mounted in the tappet barrel, said upper plunger having arecess, a ring seal in said recess coacting with said barrel, and areturn spring between the upper and lower plungers effective to move theupper plunger for extending the length of the assembly while maintainingthe cup seal tightly against a body of hydraulic fluid in the tappetbarrel.

References Cited in the file of this patent UNITED STATES PATENTS Re.21,931 Voorhies Oct. 21, 1941 2,101,917 Plater Dec. 14, 1937 2,213,195Banker Sept. 3, 1940 2,394,354 Barr Feb. 5, 1946 2,570,854 Pierce Oct.9, 1951

